gtjlcher



2 Sheets-Sheet l.,

(No Model.)

R. J. GLCHER.

THERMO ELECTRIC GENERATOR.

No. 383,464. Paftented May 29, 1888.

AnmrN u jjvvenm/ @5%. M; j

2 Shets-Sheet 2.

(No Model.)

R. J. GLCHER.

THERMO ELECTRIC GENERATOR.

Patented May 29, 1888.

lll/m76 l.

y Ma/M UNITED STATES IPATENT OFFICE.

ROBERT JACOB GLCHER, OF BERLIN, GERMANY.:

THERMO-ELECTRIC GENERATOR.

SPECIFICATION forming part of Letters Patent No. 383,464, dated May 29,1888 Applicatie-n filed tl'annnry 18, 1888. Serial No. 261,130. (Nomodel.)

thermoelectric elements inwhich adirect conversion of heat intoelectricity is effected aocording to known thermo-electric principles;and it has for its object on the one handtoincrease the useful effect ofthese elements, and on the other hand to adopt such arrangements as willafford advantages in their practical construction. These conditions are,in the first instance,complied with by making the thermoelectricbars ofwhich the elements or piles are composed, not, as heretofore, of solidbodies, but of hollow bodies, and so arranged that only their smallestbase-surfaces are used for heating, while all the other surfaces areused for cooling the elements. By this means notonly is theelectro-motive force produced greater for one and the same expenditureof heat and the same mass of thermo-electric materiahbut also, as provedby experiment, the proportion of the length of the thermo-electric barsto their outer diameter, which is necessary for producing the greatestuseful effect, is more favorable than heretofore. Thus while, forinstance, with a solid cylindrical bar of a certain alloy, the greatestelectro-motive force was obtained when the length of the bar was fromeight to ten times greater than the diameter, the requisite proportionbetweenelength and diameter for producing the greatest effect wasreduced-to from 0.9 to 1.0 when the bar was made hollow, while retainingthe same outer diameter, and with this construction the electro-motiveforce ofthe hollow cylinder was electrical resistance of thethermo-electric eleA ments is considerably decreased, so that by the useof hollow bodies in place of solid bars and having the current of gas'entering from below. Fig. 9 is a vertical section through a batterybuilt up of a series of single elements, as shown in Figs. 7 and 8.Figs. 10 and 11 show, respectively, a vertical section and a plan viewof two single thermo-electric elements arranged one within the other.Fig. 12 isa cross-section on line G H in Fig. 10.

The simplest form 'of hollow body which is suitable for the purposes ofthe present invention vis the above-mentioned hollow cylinder shown .atFig. 1 of the accompanying drawings. With this form only the annularsurface ais heated, while the other surfaces, b c d, serve for radiatingthev heat, and consequently forfcooling the element. The annularsurfaces a and c form the two poles of the element. The hollow bodiesmay, however, receive other forms suitable'for the said purpose. Theymay, for example, be formed as hollow parallelolpipedsof square,rectangular, triangular,` or

other polygonal cross-section, o`r as hollow cones or frustums,pyramids, and thelike. The essential feature o f the present inventionis the same in either case-namely, that of forming the element as ahollow body. The cause has not as yet been fullyexplained; but it is afact, determined by long-continued experiments, that even without acontinual increase of the section through which the current passes (aswith cones, pyramids, 8vo.) the proportion between the length and theouter diameter of the .thermo-electric bars requisite for producing thegreatest effect is a much more favorable one than heretofore when thesebars are made of hollow bodies. The total amount of cooling-surfaceplays only a subordinate part in this ph nomenon, as is shown by theabovementione example.

I will now describe the different modifications of the above-describedimproved construction of thermo-electric elements by the use of hollowbodies, as also the combinations of these with known and newarrangements for practically carrying out the invention.

In the first plaee,the inner space of the holro low body may be utilizedby the introduction therein of a solid. bar, also of thermo-electricmaterial, as shown in Fig. 2. The surfaces, a a, to be heated areconnected by a metal piece, a', which serves both for conveying the heatx5 to these surfaces, as also for the conductingconnection thereof. Theaction of such a compound element can, however, as is shown by what hasbeen 'before stated, be considerably increased if,in place ofintroducingasolid bar,a zo second hollow body is introduced into thefirst one. The form of such inner hollow body may be similar to that ofthe outer one, or it may be different therefrom. The inner hollow bodymay also be either of the same material as the louter one, or it may beof a different thermo-clectric material, as shown at Fig. 3. The twohollow bodies are in this case supposed to be connected in series; butthey may also be arranged in parallel. When 3o the two hollow bodies areof different material, they may, of course, also be either of the sameor of a different form.

Fig. 3 shows, by way of example, the combination of two hollowcylinders. Fig. 4 shows 3 5 the combination of a hollow frustum of acone with a hollow cylinder. The action of such a combined element mayalso be further increased by providing the inner hollow body withair-holes Zsomewhat below the edge of 4o the outer hollow body, as shownat Fig. 4. In each pair of elem-ents there is then produced a continuouscirculation of air, that assists the cooling thereof, the air enteringthe interior of the larger hollow body and passing through theair-holesinto the interior of theinner body, from the end of which itagain escapes into the atmosphere, as indicated by the arrows. Thiscirculation of air and its beneficial action are increased it' the outeropen end of the inner 5o body is provided with a chimney or air-flue, C,Fig. 5. These latter may be made of suitable material; but they must beso formed'that y in building up several elements to form a pile orbattery the current of warm air rising up from the chimneys does notcome in contact with the elements above it or their chimneys. For thispurpose it is ad vautageons to arrange the chimneys at a sufficientinclination, W, from the vertical, as shown at Fig. 5.

Astill better action is produced if the chimneys or air-dues C of eachpair of elements are led, insulated from each other, to the heatingspacecommon to all in such manner that this space is quite isolated from theouter air, and is only fed with warmed air from the chimneys in. asimilar manner to the regenerative heating and lighting apparatus. Fig.6 shows-a diagram of such an arrangement with a thermocolumn composed ofseveral elements. A A are the outer and B B the inner hollow bodies ofthe elements.

O G are the insulated air-lines, which conduct the warmed air into thecommon heat-ingchambcr, where it effects the combustion of the gasesissuing from the Bunsen burner E. The arrows in dicate the direction ofthe aircurrents. The several elements are insulated from each other andfrom thc heating-chamber, and can be arranged either inparallel or inseries.

The combustion-gases rising in the combustion-chamber draw the airrequired for the combustion from the due C, whereby on the one hand thecirculation of thc air, and con sequently the cooling of the elements,is increased, and on the other hand the combustible gases are fed withwarmed air,whereby an increased heat is produced in thecombustionchamber. Thus both an increased cooling and an increasedheating of thc elements are et"- fected, resulting in an increasedproduction of electro-motive force.

In addition to the hcreinbefore-staied advantages that arise from theuse of hollow bodies and their combinations to thermo electricelements', and which have the effect of producing a comparatively highelcctromotive force with a small internal resistance of the elements,other important advantages may be attained thereby, which with thesimplest possible construction result `in the best possible utilizationof the source of heat, and conse-- quently also a very considerablesaving of fuel.

- Although an apparatus constructed according to the arrangement shownin Fig. 6 already acts more economically than the thermo-columnsheretofore used for the above-stated reasons, yet the loss of heat withsuch an apparatus is still considerable. ing-chamber absorbs for theheating of its walls, from which the heat is transmitted to theelements, a considerable amount of heat;-

furthermore, a large quant-ity of heat escapes upward from theheating-chamber and is entirely lost; and, lastly, the heating apparatusitself (i. e., at Fig. 6 the Bunsen burner E) absorbs considerable heatwithout utilizing such heat for the production of electricity. Theseconsiderable losses of heat are entirely obviated if the elements formedof hollow bodies are so arranged that they 'can themselves be made toserve as their own heating apparatus. This is effected, in the firstinstance, if thel inner hollow body of each pair of elements is used forthe conductionv of the combustible gases, and if the ends of both thehollow bodies that have to be heated are provided with one or moreopenings communicating with the inner hollow body, through which thegases can issueand can enter into combustion immediately at the ends ofthe hollow bodies that have to be heated. Thus if, for example, as shownat Fig. 7 such a pair of elements is arranged vertically with theheatedends downward, the

IOO

The common heat- IIO ' interior ofthe inner body, B,being connected withthe gas-supply pipe and the gas issuing from a small hole in the bottombe ignited, it

lwill in burning apply itself in circular form to the commonconnecting'plate a', (as on account of its lowerspecific gravity it willtend 1 to rise on issuing,) coming all round in contact with the air,andthus producing perfect combustionthat is, producing a blue smokelessilame,1as"with a Bunsen burner. The heat thusproduced is by thisarrangement almost entirely absorbed by the end of the pair of elementsto be heated, and it is sufficient to providethe vplate a with a disk,F, of mica,`

asbestus, or other bad conductor otl heat, of a larger diameter than theend of the outer body,

A, in order to protect the upper part of the latter from the -radiatedheat ofthe flame and `the current of hot air rising up therefrom.

`'Ilie'gas passing down through the inner body,

vB, also has a cooling eiect upon the upper 5 part thereof. The sameresult is obtained if a simllarpair of elements is placed in aninvertedvertical position, as at Fig. 8,' a plate, ai, being xed at a certaindistance from the upper end. By this means the issuing gas is spreadout, andin that case also burns with a vblue iame, which will be incontactl withthe .surface'of the plate a', so as to heat the same.

`neously, of fuel. The upper pair of elements are, as 40 As, however, bythis arrangement, lthe heat given o" to the plate a2 will be lost, itWill be evident -that it would be of advantage to replace that plate bya second pair of elements, having its heated end a2 downward, as at Fig.9, thus leaving a space between the two in which the dame burns, so thatthis serves to heat the two pairs of elements simultathus effectingastill greater economy `may be made to pass down through the upper ones,as at Fig. 7 but the arrangement shown at Fig. 9 would appear to be the,most practical. Fig. 9 also shows the arrangement for combining severalpairs of elements to a pile or battery. J is a hollow stand, which isconnected lby a nozzle with the gas-supply, and

-from which the gas 'pacs into the several lower inner hollow bodies, B,fixed thereon, the corresponding set of upper elements being carriedby astandard, H, having radial arms G. The combination of two hollowthermoelectric bodies arranged one within the other may, lastly, also bearranged with much ad vantage for forming their own heating apparatus insuch manner that instead of 'heating their surfaces from the outsidetheyare -heated from the inside. Figs. 10, '11, and 12 show, respectively, avertical section, a plan, and a cross-section at G H, Fig. 10, of suchan arrangement.

.up through the latter.

The inner hollow body, B, serves to conduct the combustible gas; but itis not connected directly with the heating-plate a', but by means of ametal piece, C, brazed into the same, of star-shaped section, in suchmanner that a space of a certain size is formed between the plate a' andthe end surface of the body B. By this Ameans there are formed withinthe edge fth'ebody B several small opeulngs, o, Fig. 12. The metal pieceC serves at the same time both for effecting the electrical connectionbetween the two hollow bodies and for transmitting the heat to the bodyB.

The outer hollow body, A, is bulged out at its base in order to affordthe tlamesuicient room within it, and it is provided with openings(preferably slits) s, th rough which the combustion-gases escape. Thebars t,'formed between these slits, are made to increase considerably intransverse section toward the basesurface,iu order that the bars t mayeffectually take up the heat and conduct it to the base a.

.of elements thus arranged are preferably xed vertically upon agas-'chamber common to all, in a manner similar to the lower pairs ofelements 'at Fig. 9. The gas passes in this arrangement up the body Band through the openings o, where it enters into combustion inside thebody A, with the airsupply rising A flame of annular shape giving vnosmoke will again result, heating the plate a to a high degree. Theheat'of the combustion-gases issuing through the slits s will, in greatmeasure, be takenI up by the bars t, which conduct. it, as above stated,to the base a. It will be readily understood that this arrangement willgive agreater useful e'ect than those previously described, not onlybecause the heat is utilized to the greatest extent, but also because bythe combustion of the gas within the body A and the issue of thecombustion-gases through the slits s a strong current of air fromoutside toward and up ythrough the bodyA is produced, whereby the loweropen' end of the latter is eiiectually cooled, and consequently thediierence of temperature between the two ends and the resultingelectro-motive force will be increased. The cooling of the body B ise'ected, as in the previous arrangements, by the current ofgas flowingthrough it. With this arrangement, how ever, a special device forigniting the gas-jet inside the element is required. This consistssimply of a two-way cock common to all the elements combined in abattery, arranged so that in one position it permits more gas to iiowthrough than is required for actuating the elements. When the cock is iuthis position, the gas issues through the slits s and is ignitedoutside, so that it burns over the element with a blue flame. After afew minutes the elements will have attained the degree of heat at whichthe above-mentioned circulation ot' air is suiciently strong to feed aninternal iame with suicient air to e'ect perfect combustion. The flamewill then shift from the outside through the slits sto the inside, whereit will Pairs IIO l the purpose set forth.

burnwithiu the edge of the body B. The cock is then turned into itssecond position, so as to supply the elements with only the amount ofgas requisite for their proper action.

It is to be understood that the pairs of elements are suitably insulatedfrom each other and from the other parts ofthe apparatus, aud

that they may be connected either iu series or `to get granted byLetters Patent of the United States, is-

1. A thermo-electric element consisting olf a l hollow cylindrical bc-dyprovided with a small base-surface at one end'for receiving heat and alarge cooling-sur face, substantially as and for 2. thermo-electricelement consisting of a hollow body provided with a small base surfacefor receiving heat and a large ceoliug-surface, in combination withsecond thermoelectric body arranged within the first one, substantiallyas and for the purpose set forth.

3. A thermo-electric. element consisting of a` hollow body provided witha small base-surface for receiving heat and a large coolingsurface, incombination with asecond hollow ther 1uoeleetric body arranged withinthe first one, substantially as and for the purpose set forth.

4. A thermo-electric element consisting of a hollow body provided with asmall base-surface for receiving heat and a large cooling-surface, incombination with a second hollow thern10-electric body arranged withinthe first one and provided with lateral air-11oles somewhat below theedge of the said outer body, substantially as and for the purpose setforth.

5. The combination, with a series of external hellow thermo-electricelements, A, of the internal elements, B, the chimneys C,conneeted tothe said elements B, and a heating-chamber common to all the elementsand connected to the said chimneys, substantially as and for the purposeset forth.

6. The combination, with an external hollew thermoelectric element, of asecond internal element provided with a central passage for gas, and aburner-hole common tcboth elements, substantiallyas and for the purposeset forth.

7. The combination of an external hollow thermo-electric element, andasecond internal element pre-vided with a central passage for gas, and aburner-hole common to both ele ments, with a second pair of external andinternal elements similar to the first pair, and

arranged with the heated ends of each pair op-

